Compensating turntable drive



y 13, 1941- a v. SCHNEIDER 2,241,483

' COMPEN'SATING TURNTABLE DRIVE I Filed Nov. 18, 1940 3 Sheets-Sheet 1my 13,1941. Ev. SCHNEIDE 2,241,483

COIPBNSATING TURNTABLE DRIVE Filed Nov. 18. 1940 3 Sheets-Shget 2 Q Q QI Q Q M R Inna) If fill/wider VZM3% May 13, 1941- v. SCHNEIDERCOIPENSATING TURNTABLE DRIVE Filed Nov. 18, 1940 3 Sheets-Sheet 3 aninduction motor for driving Patented May 13, 1941 2,241,483 COMPENSATINGTURNTABLE DRIVE Emmor V. Schneider, Alliance, Ohio, assignor to TheAlliance Manufacturing Company Alliance,

Ohio, a corporation of Ohio Application November 18, 1940, Serial No.366,056

14 Claims.

as the usual commercial records. and this has resulted in a growingdemand for combination recording and reproducing phonographs for homeuse.

Such phonograph-s are relatively inexpensive, and, for this reason. areusual provided with e turntable, because such motors are economical inconstruction.

It has been found 'by experience, however, that turntable drivesoperated by such inexpensive motors are not entirely satisfactorybecause the motor does not have suflicient power to drive the turntableat a uniform speed from thestart to the end of arecord, especially inrecording. and the turntable is driven more rapidly" when reproducingthan when recording.

Experience has shown that in recording upon such phonographs as are nowin general use for home recording and reproducing, there is adifferential of approximately eighteen inch ounces to six inch ouncesbetween the start and the end of the record. I

This results in noticeable variations in both the tempo and pitch ofrecordings made upon such phonographs.

It is also well known that there is a diflerenoe of approximately fourrevolutions per minute berecording and playing of records and minimizethe pulsations or vibratiom of the motor.

A further object of the invention is to provide a turntable drive inwhich the turntable is frictionally driven by a tapered pulley upon themotor shaft, said pulley being arranged to move vertically relative tothe turntable to compensate for variations in the speed of the tumtablebetween the start and the end of a recording, or between the recordingand reproducing of a rec- 0rd.

Another object of the invention is the provision of such a turntabledrive in which the tapered pulley is driven through a torsion springwhereby the pulsations and vibrations of the motor will not bereproduced in the recording or playin of a record.

Still another object is the provision of a turntable drive of thecharacter mentioned in which the tapered pulley is moved verticallyrelative to the turntable by means of a continuous helical rib or threadhaving a sui'iiciently steep pitch'to accomplish the desired result.

A further object of the invention is to provide a turntable drive ofthis general type in which the tapered pulley is mounted for relativelongitudinal and rotary movement upon the motor shaft.

A still further object is the provision of such a turntable drive inwhich the tapered pulley is provided with a depending skirt whichencloses tapered friction pulley is arranged to be driven by the motorand in turn to drive the turntable. with means for automatically movingthe tapered p lley vertically, relative to the turntable; and for thepurpose of illustration certain forms of the invention, wherein thetapered pulley is mova-ble relative to the motor shaft, are shown in theaccompanying drawings. in which Pig. 4, an enlarged, longitudinal,sectional view of a slightly modified form of tapered pulley.

Fig. 5, a similar view of another modification of the inpered pulley;

Fig, 6, a similar view of a still further modification showing thepulley provided with a compression spring rather than the torsionsprings shown in the other forms of the invention, and

Fig. 7, a fragmentary top plan view of the improved compensatingturntable drive, with parts of the turntable broken away for the purposeof illustration.

Similar numerals refer throughout the several views.

In Fig. 1 is shown a portion of a phonograph provided with the improvedturntable drive in which the platform of the phonograph cabinet isindicated generally at H) and the turntable I l is rotatably mountedupon the spindle l2 and provided with the usual depending peripheralflange l3 arranged to be driven by frictional contact with the rubber orsimilar rim l4 upon the wheel I5 which is in the nature of an idlerpulley rotatably mounted upon the spindle l6, which is carried by aplate H5 slidable toward and from the flange l3 of the turntable andpulley 23.

The general assembly of the turntable drive is the same as disclosed inmy co-pending application, Serial No. 294,938, filed September 14, 1939,and, as shown quite clearly in Fig. '7, the sliding plate I6 is mountedfor sliding or swinging movement upon the motor mounting plate 2%, bymeans of the screw 40 which is threaded into the motor mounting plateand located through an enlarged aperture M in the plate IS, a flanged tosimilar parts washer 42 spacing the head of the screw so as nottobindthe plate l6 and at the same time covering the enlarged opening 4l A downturned lug 43 is formed at the inner end of the sliding plate Itfor sliding movement within the slot 44 formed in the motor mountingplate 20, a spring 45 being connected to the sliding plate It and to theadjacent edge of the motor mounting plate to urge the tire I! of thewheel I5 into frictional contact with the rim i3 of the turntable andthe pulley 23.

The motor may be of the usual induction type comprising the field coill1 and the squirrel cage type rotor I8, this motor being suspended as bythe rods [9 from a plate supported upon. the platform l0 as by therubber grommets 26,

The motor shaft 22, which is operatively conneoted to the rotor of themotor is usualiy'provided with a friction pulley engaging the peripheryof the friction wheel l5 for frictionaliy driving the turntable l ithrough said friction wheel.

Under present practice the friction pulley is fixed upon the motor shaftwhich is concentrically fixed to the rotor.

In order to carry out the present invention the friction pulley islongitudinally and rotatably movable relative to the rotor and this maybe accomplished by providing for relative longitudinal and rotatablemovement between the shaft and the rotor or as illustrated and describedin detail herein by providing for relative longitudinal and rotarymovement between the pulley and the shaft.

Instead of the conventional straight or cylindric pulley as used inpresent practice the invention contemplates the provision of a taperedpulley indicated generally at 23 for frictionally driving the idlerwheel i5.

The upper end of the motor shaft 22 may be provided with a thread orcontinuous helical rib of rather steep pitch as indicated at 23 and thepulley 23 may be hollow as shown in Fig. 2 and provided at its upper endwith similar internal threads providing for relative longitudinal and aate-s3 rotatable movement of the pulley upon the shaft. As best shown inFigs. 2 and 3, the threaded portion 24 of the shaft 22 is reduced indiameter and the extreme upper end of the shaft is fur- 5 ther reducedand threaded as at 25 to receive a nut 21.

A transversely disposed stop pin 28 is located through the upper end ofthe reduced threaded portion 25 of the shaft and a notch 29 is formed inthe upper end portion of the pulley 23 for engaging therewith as bestshown in Fig. 2 for limiting the upward movement of the pulley upon theshaft.

A helical torsion spring 30 flexibly connects the pulley to the shaft,the upper end of said spring being provided with a hooked portion 3|attached to the pulley while the lower end of the spring is providedwith a hooked portion 32 attached to the transverse lower stop pin 33,

For the purpose of enclosing and protecting the spring, a skirt 34 maydepend from the lower end portion of the pulley surrounding the springand provided at its lower end with a notch 35 to receive the lower stoppin 33 of the shaft and limit the downward movement of the pulley.

In the normal position of the parts as shown in Figs. 1 and 2, thespring 39 holds the pulley 23 at the upper end of the shaft, the notch29 receiving the upper stop pin 28 and preventing further movement ofthe pulley in this direction, the smaller end of the pulley being infrictional contact with the wheel i5.

In the operation of the phonograph, as the pressure of the needle uponthe record offers re sistance to the rotation of the turntable, thespring 30 will be wound up rotating the pulley upon the shaft in adirection whereby the screw threads cause the pulley to move downwardbringing a larger diameter thereof into contact with the friction wheell 5.

Thus, the device compensates for changes in torque upon the turntableand provides for a smooth uniform rotation of the turntable throughoutthe entire recording or playing of a record.

Furthermore, the spring connection between the shaft and the pulleyabsorbs the pulsations or vibrations of the induction motor causing asmooth continuous rotation of the turntable.

In Fig. 4 is shown a slightly modified form of the invention in whichthe motor shaft 22 has its upper end portion reduced as at 26 and screwthreaded intermediate the ends of the reduced portion as at 24 forengagement with the internal screw threads 25 upon the tapered pulley23.

An upper stop pin 28 is fixed upon the upper end of the reduced portionof the shaft and a lower stop pin 33 is fixed upon the shaft in positionto contact with the inwardly disposed stop lug 35*- upon the skirt 34 ofthe pulley.

The spring 30 may be tapered as shown, and provided with the upper hook3| for engage- .ment with the pulley and the lower hook 32 forengagement with the lower stop pin 33.

The upper end of the pulley may be notched as shown at 29 for receivingthe upper stop pin 28*.

The operation of this form of the invention will be the same as abovedescribed.

In Fig. 5, the shaft 22 has its upper end reduced and threaded with alarge thread of very steep pitch as indicated at 24 and the pulley 23has the depending skirt 34 having the upper and lower stop lugs 29 and35 respectively,

for engagement with the stop pin 33" upon the shaft.

The spring 30" has the upper hook 3| connected to the pulley and thelower hook l2 connected to the pin 33". i

A cap 31 may be connected to the top of the pulley to close the centerbore thereof. the cap being held in place by a flange 3B which is spunover the edge of the cap.

The operation of this form of the invention .will be the same as abovedescribed.

In Fig. 6 is shown another modification of the invention in which thecoil spring 30 is a compression spring but not a torsion spring.

In this form of the invention the upper end of the shaft 22 is threadedwith a steep pitched square thread or continuous helical rib 26 andprovided with a cap 31 at its upper end.

The tapered pulley 23 is internally threaded as at 25 A depending skirt34 surrounds the spring 30 and the stop pin 33 is adapted to contact thelower end of the skirt to limit the lower movement of the pulley whilethe cap 31 is provided to contact the upper end of the pulley to limitthe upper movement thereof.

Otherwise, the operation of this form of the invention is as abovedescribed.

I claim:

1. A phonograph turntable drive including a turntable, a motor, a shaftupon the motor, a tapered friction pulley threaded upon the motor shaft,a friction wheel normally frictionally contacting the smaller end of thetapered pulley and the turntable, and torsion spring means for movingsaid tapered pulley longitudinally upon the motor shaft so as to bring alarger portion of the tapered pulley into contact with the frictionwheel by variations in drag upon the turntable to compensate forresultant variations in speed of the turntable.

2. A phonograph turntable drive including a turntable, a motor, a shaftupon the motor, a tapered friction pulley upon the shaft, meansfrictionally associating said tapered pulley with the turntable, saidmeans including a friction wheel normally frictionally contacting thesmaller end of said tapered pulley, and torsion spring and screw meansfor producing relative movement between the tapered pulley and thefriction wheel so as to bring a larger portion of the tapered' pulleyinto contact with the friction wheel by variations in drag upon theturntable to compensate for resultant variations in speed of theturntable.

3. A phonograph turntable drive including a motor, a tapered frictionpulley operatively connected to said motor, a turntable, meansfrictionally associating said pulley with the turntable and torsionspring and screw means for moving the tapered pulley axially relative tothe turntable to compensate for variations in drag and resultant speedchanges of. the turntable.

4. A phonograph turntable drive including a motor, a tapered frictionpulley operatively connected to-said' motor, a. turntable, meansfrictionally associating said pulley with the turntable and torsionspring and screw means controlled by torque and resultant speed changesof the turntable formovlng the tapered pulley axially relative to theturntable to compensate for variations in torque and speed of theturntable.

5. A phonograph turntable drive including a motor, a tapered frictionpulley operatively connected to said motor, a turntable, meansfrictionally associating said pulley with the turntable and torsionspring and screw means controlled by drag upon the turntable for movingthe tapered pulley axially relative to the turntable to compensate forresultant variations in speed of the turntable, and means for limitingthe axial movement of the tapered pulley in each direction.

6. A phonograph turntable drive including motor, a shaft upon the motor,a threaded portion upon the shaft, a tapered friction pulley threadedupon the shaft, stop means upon the shaft for limiting movement of thepulley in one direction, torsion spring means for urging the pulleytoward said stop means, a turntable and means frictionally associatingthe pulley with the turntable whereby the tapered friction pulley ismoved axially upon the shaft by variations in drag to compensate forresultant variations in speed of the turntable.

'7. A phonograph turntable drive including. a motor, a shaft upon themotor, a threaded portion upon the shaft, a tapered friction pulleythreaded upon the shaft, stop means upon the shaft for limiting movementof the pulley in one direction, torsion spring means connected to thepulley and to the shaft for urging the pulley toward said stop means, atm'ntable and means frictionally associating the pulley with theturntable whereby the tapered friction pulley is moved axially upon theshaft by variations in drag to compensate for resultant variations inspeed of the turntable.

8. A phonograph turntable drive including a motor, a shaft upon themotor, a threaded portion upon the shaft, a tapered friction pulleythreaded upon the shaft, stop means upon the shaft for limiting movementof the pulley in one direction, torsion spring means for urging thepulley toward said stop means, a depending skirt upon the pulley,housing said spring means, a turntable and means frictionallyassociating the pulley with the turntable whereby the'tapered frictionpulley is moved axially upon the shaft by variations in drag tocompensate for resultant variations in speed of the turntable.

9. A phonograph turntable drive including a motor, a shaft upon themotor, a threaded portion upon the shaft, a tapered friction pulleythreaded upon the shaft, stop means upon the shaft for limiting movementof the pulley in one direction, torsion spring means for urging thepulley toward said stop means, a turntable and means frictionallyassociating the pulley with the turntable whereby the tapered frictionpulley is moved axially upon the shaft by variations in drag on theturntable which otherwise would result in speed changes of theturntable, and

means for limiting axial movement of the pulley upon the shaft in theopposite direction.

10. A phonograph turntable drive including a motor, a shaft upon themotor, a threaded por- 'tion upon the shaft, a tapered friction pulleythreaded upon the shaft, stop means upon the ly connecting saidperipheral flange and'said taperedpulley whereby the tapered frictionpulley is moved axially upon the shaft by variations in drag tocompensate for resultant variations in speed of the turntable.

11. A phonograph turntable drive including a motor, a shaft upon themotor, a. threaded portion upon the shaft, a tapered friction pulleythreaded upon the shaft, stop means upon the shaft for limiting movementof the pulley in one direction, torsion spring means for urging thepulley toward said stop means, a turntable having a. peripheral flange,a slidable plate, a friction wheel journaled upon said slidable plateand frictionally connecting said peripheral flange and said taperedpulley whereby the tapered friction pulley is moved axially upon theshaft by variations in drag to compensate for resultant variations inspeed of the turntable.

12. A phonograph turntable drive including a turntable, a motor, atapered friction roller operatively connected to the motor, a. frictionwheel contacting the tapered friction roller and the turntable, andtorsion spring and screw means for producing relative axial movementbetween the tapered friction roller and the friction wheel to compensatefor variations in drag and resultant speed changes of the turntable.

13. A transmission including a driving means, a. tapered friction rolleroperatively connected to said driving means, a friction wheelfrictionally associated with the tapered roller, driven meansoperatively associated with the friction wheel, and torsion spring andscrew means for moving the tapered roller axially relative to thefriction wheel to compensate for variations in drag and resultant speedchanges of the driven means.

14. A transmission including a driving means, a tapered friction rolleroperatively connected to said driving means, a friction wheelfrictionally associated with the tapered roller, driven meansoperatively associated with the friction wheel, and torsion spring andscrew means for producing relative axial movement between the tapered nroller and the friction wheel to compensate for variations in drag. andresultant speed changes of the driven means.

EMMOR V. SCHNEIDER.

